1. Field of the Invention
The present invention relates to a signal transfer method for transferring multi-bit signals over a transfer path which is allocated to one bit.
2. Description of the Related Art
Conventionally, two signal lines are employed for transferring signals having values of "0" or "1". At the transmission end of the transfer path, voltages which are selected in accordance with a particular value of a signal for transmission are applied to the two respective signal lines. At the receiving end of the transfer path, the difference between the voltage which is applied to one of the signal lines and the voltage which is applied to the other signal line is detected. For example, if the detected difference is larger than a predetermined voltage value, the received signal may be determined as having the value "1", and if the detected difference is smaller than the predetermined voltage value, the received signal may be determined as having the value "0". Such a pair of signal lines is usually referred to differential signal lines.
As a method for transferring a signal which may take one of three or more values (hereinafter such a signal will be referred to as a "multi-value" signal) over such a pair of differential signal lines, a method is known in which the range between a voltage corresponding to the "0" value and a voltage corresponding to the "1" value is divided into a plurality of regions, for example. According to this method, any values other than "0" or "1" can be assigned to the respective divided regions.
However, the aforementioned conventional method for transferring multi-value signals, which involves dividing a range between a voltage corresponding to the "0" value and the voltage corresponding to the "1" value into a plurality of regions, can only provide a small margin for the determination of signal values at the receiving end. This increases the likelihood of misdetecting signal values at the receiving end.